PayDay

Invoice financing through a smart contract on Avalanche: small businesses get paid today instead of waiting 90 days, and the contract handles the rest.

Winner of the Revoluchain hackathon (Prilep, October 2026), backed by Avalanche team1.

How it works

1. Business issues an invoice on-chain (amount, client, due date).
2. Client confirms the debt from its own wallet, so there are no fake invoices.
3. Business lists the invoice for sale at a discount.
4. Investor buys it. The money goes to the business and ownership goes to the investor in one transaction.
5. Client pays on the due date, and the money goes automatically to whoever holds the invoice.

The contract also refuses to let an invoice be sold twice, records whether each payment was on time or late, and keeps a public payment record for every client.

Project layout

Path	What it is
contracts/PayDay.sol	The smart contract (Solidity 0.8.20+)
test/PayDay.t.sol	Foundry tests for every contract rule
app/index.html	The web app: Business, Client, Investor and Public board views, with a built-in demo mode
foundry.toml	Foundry settings (compiler 0.8.24, 1,000 fuzz runs per fuzz test)

Run the tests

Needs Foundry (forge).

forge test                       # run all tests
forge test -vvv                  # with details on any failure
forge coverage --report summary  # how much of the contract the tests exercise

Current result: 42 tests passing, 100% line, branch and function coverage of PayDay.sol. The tests cover invoice creation rules, client-only confirmation, listing and price limits, the atomic buy, double-sale rejection, resale, on-time vs late payment, overdue status, and fuzz tests with random prices and payment times.

Run the app locally

python3 -m http.server 8000 --directory app

Then open http://localhost:8000 in Chrome. That's the landing page; the app is at /app.html.

• Live mode (default): talks to the deployed Fuji contract. Anyone can read the invoices; connect MetaMask on Avalanche Fuji to act. Opening the page from http://localhost is required, because MetaMask doesn't connect to pages opened as files. ?c=0x… points the app at another deploy.
• Demo mode (/app.html?demo): a simulated chain in the browser with the same rules as the contract. No wallet needed.

Deployment

Live on Avalanche Fuji testnet (C-Chain, chain ID 43113), source verified on Snowtrace.

Website: https://paydayinvoice.vercel.app (landing) · https://paydayinvoice.vercel.app/app (app) · hosted on Vercel, deploys automatically on every push to main (root directory app/).

Contract	0x9983d1f7aF8328a92cFb76cBeb12c7894D14D0Ed
Deploy transaction	0x94a7520c…3309a
Block	60051288
Deployed	26 October 2026

The app has this address built in (CONTRACT in app/app.html).

Status

Hackathon prototype on the Avalanche Fuji testnet. Not ready for mainnet or real funds. Before mainnet it needs: stablecoin payments, private invoice data (hash only on-chain), verified companies, pull payments, an emergency pause, a way to cancel or reprice a listing, and an independent security audit.

Two of these limitations are pinned down by tests, so the fix can be checked later:

• test_KnownIssue_RejectingHolderBlocksClientPayment: if the invoice holder's wallet refuses AVAX, the client cannot pay at all (fix: pull payments).
• test_List_RepriceWhileListed_Reverts: a listed invoice cannot be repriced or taken off the market.